The Collaborative International Dictionary of English v.0.48:

Bumble \Bum"ble\, n. [See Bump to boom.] (Zool.)
   The bittern. [Local, Eng.]
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Bumble \Bum"ble\, v. i.
   To make a hollow or humming noise, like that of a bumblebee;
   to buzz; to cry as a bittern.
   [1913 Webster]

         As a bittern bumbleth in the mire.       --Chaucer.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Bumble \Bum"ble\, v. i.
   to act ineptly or without clear understanding of what one is
   doing; to blunder; to stumble about; -- sometimes used with
   around.
   [PJC]

The Collaborative International Dictionary of English v.0.48:

Bumble \Bum"ble\, v. t.
   to bungle (a task).
   [PJC]

WordNet (r) 3.0 (2006):

bumble
    v 1: make a mess of, destroy or ruin; "I botched the dinner and
         we had to eat out"; "the pianist screwed up the difficult
         passage in the second movement" [syn: botch, bodge,
         bumble, fumble, botch up, muff, blow, flub,
         screw up, ball up, spoil, muck up, bungle,
         fluff, bollix, bollix up, bollocks, bollocks up,
         bobble, mishandle, louse up, foul up, mess up,
         fuck up]
    2: walk unsteadily; "The drunk man stumbled about" [syn:
       stumble, falter, bumble]
    3: speak haltingly; "The speaker faltered when he saw his
       opponent enter the room" [syn: bumble, stutter,
       stammer, falter]

Moby Thesaurus II by Grady Ward, 1.0:

38 Moby Thesaurus words for "bumble":
   be all thumbs, blow, blunder, blunder away, blunder into,
   blunder on, blunder upon, bobble, boggle, bollix, bombinate, botch,
   bum, bungle, butcher, buzz, commit a gaffe, drone, faux pas,
   flounder, fumble, lumber, lurch, mar, miscue, mucker, muddle, muff,
   murder, play havoc with, screw up, slip, snapper, spoil, strum,
   stumble, thrum, trip